A vehicle electrical system includes a battery, an engine, and an alternator among other components. The battery is typically used to supply a starter motor with electrical energy for starting the engine. The engine includes a rotating output that is used to drive a transmission of the vehicle for moving the vehicle. The alternator is connected to the rotating output of the engine and operates as an electrical energy generator. In particular, the alternator converts mechanical energy from the operating engine into electrical energy for consumption by the vehicle. In a common configuration, the electrical energy from the alternator charges the battery so that the battery is maintained at a state of charge sufficient for starting the engine.
The typical alternator includes a stator and a rotor shaft supporting a field coil. The field coil is located in proximity to the stator, and a belt connects the rotor shaft and field coil to the rotating output of the engine. Operation of the engine results in rotation of the rotor shaft and the field coil relative to the stator. Current flowing through the rotating field coil induces a corresponding current in the stator. The corresponding current of the stator is rectified and conditioned to provide electrical energy for consumption by the vehicle.
In addition to generating electrical energy, the alternator also generates heat. Specifically, the electrical interaction between the field coil and the stator heats the field coil and the stator. This heat radiates to each other component of the alternator and increases the overall temperature of the alternator. Typically, it is desirable to maintain the alternator within a particular range of operating temperatures; thus, most alternators include at least one fan that is configured to expel heat from the alternator. However, as customers require more output out of smaller machines, improved cooling methods become desirable, because prior art cooling methods are not optimized for cooling modern alternators. For example, a prior art alternator may include an internal fan and an external fan. In response to being rotated, the internal fan generates a first airflow and the external fan generates a second airflow. Instead of working together to optimally cool the alternator, portions of the airflows generated by the fans interfere and conflict with each other, thereby resulting in a non-optimized configuration that does not cool the alternator in the most effective manner. In the worst case, exhaust air from one fan tries to exit an outlet opening that also acts as an inlet opening for the other fan, resulting in interference of the airflows, such that efficient cooling of the alternator is diminished. In another example, a prior art alternator may include internal fans which are too small to effectively cool a high power alternator, or an external fan which is unable to provide desired cooling to all components simultaneously.
Based on the above, further developments in the area of cooling fans for alternators are desirable.